To keep children away from danger,we warn parents ________ children at home alone.
A:leave
B:to leave
C:not leave
D:not to leave
284×30=( )
“绿叶在光下制造有机物”的实验中,其中一个步骤是对绿叶进行脱色(如图),图中大、小烧杯内放置的液体分别是( )